Telomeres: if you could, would you live forever?

In the ever evolving world of science the legendary idea of immortality may no longer be an impossible concept. In an attempt to fight against cancers, eye disease and some gastrointestinal disorders, scientists have discovered a way to prevent cell degeneration and death in order to treat or delay the onset of various diseases.

There are various reasons why we age, one of them being oxidative stress. This is when highly
reactive molecules containing oxygen, called oxidants, cause damage to our DNA, as well as the proteins and lipids in the body. Oxidants can be produced naturally though respiration or through infections and inflammation, but also through certain life-style choices such as consumption of alcohol and cigarettes.

However one of the main the events associated with aging cells is related to telomere length. In order to grow and function normally, cells in our bodies need to divide to replace damaged cells. During the process of cell division, copies of the genetic material must pass on to the next generation of cells. The genetic information inside cells is arranged in twisted strands of DNA called chromosomes. At the end of these strands is a protective ‘cap’ known as a telomere. Telomeres can be said to be like the protective end of a shoelace which prevent the strands from unraveling, deteriorating and sticking onto neighbouring chromosomes. The deterioration and sticking to other chromosomes may cause a loss of genetic information which can lead to cell disease and even death. Telomeres therefore are necessary units for the expression of our genetic data. Each time a cell divides the protective telomere ‘cap’ gets shorter. When they get too short, the cell loses its ability to renew and divide and becomes inactive (senescent) or dies. This is what leads to cell death.

Therefore in an immortal animal we would expect cells to be able to maintain telomere length
indefinitely so that they can continue to replicate. Scientists have now associated telomere length to life span. It has been shown that shorter telomeres are linked to people having shorter life spans. Specifically, when studying people over 60 years of age, they discovered that those with the shortest telomeres where three times as likely to die from heart disease and eight times more susceptible to infectious diseases. The enzyme called telomerase lengthens the ends of the telomeres. In young cells the telomerase keeps the telomeres from wearing down too much, but as the cell continues to divide and grows old, the levels of telomerase decreases, so the telomeres grow shorter and the cells age.

Telomerase has been linked to cancer. Cancerous cells are those that grow uncontrollably, owing their ability of continuous growth by being able to stimulate production of telomerase, making the telomeres longer, giving them an unlimited lifespan. Telomere research has fuelled cancer researchers to develop a way to potentially switch off telomerase in cancerous cells which would stop cancer developing. The big question now is, if telomerase can cause cancer cells to be immortal, could it also stop normal cells from aging? Scientists are not yet sure. However recent advances are getting close to an answer.

Current studies have demonstrated that biological immortality does exist to some extent in some species of flatworm which can overcome the aging process. The work into the mechanics of this feature may highlight new strategies for alleviating aging and age-related problems in humans, possibly relating to the maintenance of telomerase activity. So far researchers have applied their findings in various human tissues to immortalize cells from certain areas of the body, such as the breast, skin, retina and colon. Unfortunately the effects of telomerase are only applied in those cells that divide; therefore for cells such as neurons that do not divide this therapy would not be applicable , meaning disorders of the central nervous system (brain and spinal cord) such as multiple sclerosis, could not be treated this way.

Despite this, no matter how much science accelerates in this area, ethical considerations are always at the heart of such a delicate matter. The aim is not increasing life span, but healthy life span. If scientists can enhance the health of cells in the body then this would delay the onset of disease say from 65 to 75 years of age. This grants the elderly with an increased quality of life, giving them more time to enjoy an independent and active life after retirement before the onset of age-related problems. Overall much more work is to be carried out in this fascinating field, so it is still be a while before we see such medical applications in regular use.